1. Technical Field
The present invention relates to a resistive random access memory, and more particularly, to a resistive random access memory using the rare earth scandate thin film as the storage medium.
2. Description of Related Art
With the evolution of the times, the development of technologies has a great progress. In particular, the digital electronic products are invented and widely used in human life. When using the electronic products, the electronic documents and digital data processed by the electronic products need to be stored in memories for caching or accessing. Generally, memories are divided into volatile memories and non-volatile memories, in which the new-generation non-volatile memories consist of ferroelectric random access memory (FeRAM), magnetoresistive random access memory (MRAM), phase-change random access memory (PRAM), and resistive random access memory (RRAM).
In application, the resistive random access memory (RRAM) includes advantages of low operation voltage, low power consumption, fast read speed, and simple structure, so that, the resistive random access memory is widely studied and evaluated. Please refer to FIG. 1, which illustrates a cross-sectional view of a conventional resistive random access memory. As shown in FIG. 1, the conventional resistive random access memory 1′ includes: a bottom electrode 11′, a resistive memory layer 12′ and a top electrode 13′, wherein the manufacturing material of the bottom electrode 11′ and the top electrode 13′ are platinum (Pt), and manufacturing material of the resistive memory layer 12′ is NiOx.
Continuously referring to FIG. 1, and please simultaneously refer to FIG. 2, there is shown a current-voltage curve plot of the conventional resistive random access memory. As shown in FIG. 1(a), initially, there is no any voltage applied to the bottom electrode 11′ and the top electrode 13′ of the resistive random access memory 1′, and the resistive random access memory 1′ shows a high resistance state. When applying a voltage to the bottom electrode 11′ and the top electrode 13, as shown in FIG. 1(b), the applied voltage drives Ni atoms of the NiO move toward the defects in the NiOx, and then the moving Ni atoms may gradually gather and form a plurality of metal filaments. Therefore, as shown in FIG. 2, the current-voltage characteristic of the resistive random access memory 1′ converts to a forming state from the high resistance state. Finally, as shown in FIG. 1(c), the metal filaments formed by the gather of the Ni atoms would connects the bottom electrode 11′ with the top electrode 13′, meanwhile, as shown in FIG. 2, the current-voltage characteristics of the resistive random access memory 1′ converts to a low resistance state from the forming state.
According to prior research literatures and records, the manufacturing material of the top electrode 13′ can also be titanium (Ti) or copper (Cu), and the manufacturing material of the resistive memory layer 12′ can also be ZrO2 or SiO2. However, regardless of the manufacturing material of the resistive memory layer 12′ is the ZrO2 or the SiO2, the metal filaments forming procedure must be executed in the conventional resistive random access memory 1′ for making the resistive random access memory 1′ include the resistance conversion characteristic. Thus, based on the above descriptions, the person skilled in the RRAM technology is able to know that the conventional resistive random access memory 1′ has the drawbacks and the shortcomings as follows:
1. For making the aforesaid resistive random access memory 1′ include the resistance conversion characteristic, it must complete the metal filaments forming procedure of the resistive random access memory 1′ in advance; however, the breakdown of the resistive memory layer 12′ may occur in the resistive random access memory 1′ when high voltage is applied to the resistive random access memory 1′.2. Inheriting to above point 1, it would yield high power consumption when the high voltage is applied to the resistive random access memory 1′ for executing the metal filaments forming procedure. The high voltages applied may also result in the breakdown (failure) device.3. Generally, the resistive random access memory 1′ needs to be executed a thermal annealing process after the resistive random access memory 1′ is fabricated; For this reason, the thermal budget of the resistive random access memory 1′ is very high. Such thermal annealing is one of possible causes that could lead to the device failure.
Accordingly, in view of the conventional resistive random access memory still having shortcomings and drawbacks, the inventor of the present application has made great efforts to make inventive research thereon and eventually provided a resistive random access memory using the rare earth scandate thin film as the storage medium.